考虑流固耦合的偏压隧道开挖扰动区岩体损伤研究

发布时间：2018-04-21 09:18

本文选题：偏压隧道 + 初始应力场　；参考：《西南石油大学》2014年硕士论文

【摘要】：考虑山岭隧道的偏压效应和地下渗流对围岩失稳的影响,在围岩开挖扰动区引入损伤变量来评价隧道的安全及稳定性。在前人大量研究成果上,总结了初始地应力场成因、分布特点以及其在隧道工程中的重要性。首先结合现场实际情况对隧道偏压的成因进行了研究分析,并详细给出了偏压隧道设计采用的两种计算方法。通过一组简单数值模拟试验,验证了地应力平衡在隧道工程中的重要性,以及在有限元软件ABAQUS/CAE实现地应力平衡的几种方法。考虑渗流对岩体的影响作用后,在前人的工作基础上引入岩石压缩系数Cf、液体弹性压缩系数CL,基于多孔介质达西定律推导出岩体介质单相渗流连续性方程新的形式；基于虚功原理和孔隙介质有效应力原理,推导出变形场的应力平衡方程。最终通过引入孔隙水压力对时间的导数作为两方程的共同自变量实现渗流与应力方程的耦合。基于有限元软件ABAQUS/CAE,分别对偏压隧道与等效不偏压隧道在考虑渗流作用与不考虑流-固耦合效应进行了多组数值仿真试验。主要对模拟结果中的地表位移、混凝土衬砌拱圈受力形态以及开挖扰动区围岩塑性区域分布进行了对比分析,确定了渗流和偏压效应对围岩力学性质的影响程度。根据连续损伤力学理论,在前人提出的弹塑性损伤模型中进一步采用了与塑性应变相关的标量损伤,并将该损伤变量应用到摩尔-库伦屈服准则中。在考虑渗流与应力场的耦合作用下,参照前人的围岩损伤过程中渗透系数演化规律,分别建立了围岩弹塑性损伤理论模型及相应的有限元数值模型。以青藏铁路西格二线-新关角隧道的工程资料作为源数据来源,基于有限元软件ABAQUS/CAE平台,通过fortran语言编写子程序USDFLD实现损伤变量的定义及其与塑性应变的耦合,对渗流影响下的偏压隧道进行数值仿真。根据模拟结果,分析偏压隧道开挖过程中应力、孔隙压力等特性的变化规律,得出了开挖扰动区围岩损伤演化规律。通过对比传统的仅采用塑性区域表征岩体失效方法,得出用损伤变量来评价围岩可靠性的优越性和合理性。
[Abstract]:Considering the bias effect of mountain tunnel and the influence of underground seepage on the instability of surrounding rock the damage variable is introduced to evaluate the safety and stability of tunnel in the disturbed area of surrounding rock excavation. In this paper, the origin, distribution and importance of initial in-situ stress field in tunnel engineering are summarized. In this paper, the causes of the bias voltage of the tunnel are studied and analyzed according to the actual situation in the field, and two calculation methods for the design of the bias tunnel are given in detail. The importance of in-situ stress balance in tunnel engineering is verified by a set of simple numerical simulation tests, and several methods to realize in-situ stress balance in finite element software ABAQUS/CAE are verified. Considering the influence of seepage on rock mass, the rock compression coefficient Cf and the elastic compressibility coefficient of liquid are introduced on the basis of previous work, and a new form of continuity equation for single-phase seepage in rock mass media is derived based on Darcy's law of porous media. Based on the principle of virtual work and the principle of effective stress in porous media, the stress balance equation of deformation field is derived. Finally, the coupling of seepage and stress equation is realized by introducing the derivative of pore water pressure to time as the common independent variable of the two equations. Based on the finite element software Abaqus / CAE, the numerical simulation experiments were carried out for the bias tunnel and the equivalent unbiased tunnel considering the seepage effect and the fluid-solid coupling effect respectively. In this paper, the surface displacement, the force form of concrete lining arch ring and the plastic zone distribution of surrounding rock in the disturbed area of excavation are compared and analyzed, and the influence of seepage and eccentric pressure on the mechanical properties of surrounding rock is determined. According to the theory of continuous damage mechanics, the scalar damage related to plastic strain is further adopted in the elastoplastic damage model proposed by the predecessors, and the damage variable is applied to the Moorl-Coulomb yield criterion. Considering the coupling of seepage and stress field, the elastic-plastic damage theory model of surrounding rock and the corresponding finite element numerical model are established according to the evolution law of permeability coefficient in the damage process of surrounding rock. Based on the engineering data of Sieger-Xinguanjiao Tunnel of Qinghai-Tibet Railway, and based on the finite element software ABAQUS/CAE platform, the definition of damage variable and its coupling with plastic strain are realized by the subprogram USDFLD written in fortran language. Numerical simulation of the bias tunnel under the influence of seepage is carried out. According to the simulation results, the variation law of stress and pore pressure during the excavation of bias pressure tunnel is analyzed, and the law of damage evolution of surrounding rock in disturbed area of excavation is obtained. By comparing the traditional method of using plastic region to characterize the failure of rock mass, the superiority and rationality of using damage variable to evaluate the reliability of surrounding rock are obtained.
【学位授予单位】：西南石油大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U451.2

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